1. Field of the Invention
This invention relates to an apparatus for detecting an abnormality in a paperlike material, where the term "abnormality" herein refers to an irregularity in some characteristic or property, for example, an abnormality in thickness, sticking of a binding tape, double pile of the papers, false banknote and so on.
2. Discussion of the Prior Art
The prior art to which this invention is directed is described in Japanese Patent Publication (KOKOKU) No. 43-25448, publication date Nov. 2, 1968. This publication shows a bill or a check sorter, in which certain special radioactive elements are beforehand instilled in a bill or a check, and the bill or check is examined as to whether it is false or not by detecting the radiant energy from the radioactive elements. The prior art to examine the authenticity of a bill or check thus requires the introduction of special radioactive elements in the bill or check beforehand.